The present invention relates to surface active agent compositions, and emulsifying agent compositions for aqueous resin dispersion and, more particularly, to a surface-active agent composition and an emulsifying agent composition for aqueous resin dispersion which are suitable for use in aqueous-system emulsion polymerization or the like of ethylenic unsaturated monomers.
As emulsifying agents for emulsion polymerization, there are conventionally used anionic surface-active agents such as alkylsulfuric ester, alkylbenzenesulfonate, dialkylsulfosuccinate and alkyl(aryl) polyoxyalkylene ether sulfuric ester, and nonionic surface-active agents such as alkyl(aryl) polyoxyalkylene ether, polyoxyethylene-polyoxypropylene block copolymer and polyoxyethylenesorbitan fatty acid ester, either alone or as mixture. The stability of an emulsion prepared with use of such a conventional emulsifying agent and the properties or the like of a film prepared from such an emulsion are not necessarily satisfactory enough and, hence, many problems are left unsolved. Specifically, emulsions prepared with use of such conventional emulsifying agents have problems in relation to polymerization stability, mechanical stability, chemical stability, freezing and thawing stability, pigment miscibility, shelf stability and the like. The mechanical stability problem, in particular, is left as a matter to be improved. Further, when a polymer film is formed from such an emulsion, an emulsifying agent used is left as liberated in the polymer film and, hence, problems including inferior water resistance and adhesion and the like arise with such polymer films. Furthermore, since drain resulting when an emulsion is destroyed by salting-out or by any other means to harvest a polymer contains much emulsion and hence causes rivers to be polluted, much labor is required for removal of emulsion.
With a view to solving such problems essential to conventional emulsifying agents, a number of emulsifying agents that are generally called reactive emulsifying agents have been proposed. For example, anionic reactive emulsifying agents include those disclosed in Japanese Patent Examined Gazette No. SHO 46-12472, Japanese Patent Laid-Open Gazette No. SHO 54-144317, Japanese Patent Examined Gazette No. SHO 46-34894, Japanese Patent Examined Gazette No. SHO 56-29657, Japanese Patent Laid-Open Gazette No. SHO 51-30285, Japanese Patent Examined Gazette No. SHO 49-46291, and the like; and nonionic reactive emulsifying agents include those disclosed in Japanese Patent Laid-Open Gazette No. SHO 56-28208, Japanese Patent Laid-Open Gazette No. SHO 50-98484, Japanese Patent Laid-Open Gazette No. HEI 1-99638, and the like. Though attempts have been made to use these reactive emulsifying agents for emulsion polymerization of various monomers, use of an emulsifying agent comprising such a reactive emulsifying agent alone often provides insufficient stability at the time of emulsion polymerization. Thus, such reactive emulsifying agents involve a problem that their inherent performance is not sufficiently exhibited; for example, polymerization does not proceed smoothly unless a reactive emulsifying agent is used in combination with a conventional emulsifying agent.
An emulsifying agent for aqueous resin dispersion described in Japanese Patent Laid-Open Gazette No. HEI 1-99638 is known as an agent that is capable of solving such a problem. Use of this emulsifying agent makes it possible to resolve the aforementioned problem considerably. With this emulsifying agent for aqueous resin dispersion, however, some emulsions exhibit insufficient mechanical stability and polymerization stability, or some films made from the emulsion have insufficient adhesion and water resistance.
Accordingly, it is an object of the present invention to provide a surface-active agent composition and an emulsifying agent composition for aqueous resin dispersion which are capable of providing for an emulsion exhibiting satisfactory mechanical stability and polymerization stability, which in turn is capable of sufficiently enhancing adhesion property and water resistance property when used to form films.
A surface-active agent composition according to the present invention comprises: a polymerizable monomer surface active agent represented by the general formula (I) as chemical formula 1 and a polymerizable dimer surface active agent represented by the general formula (II) as chemical formula 2: 
wherein, in chemical formulae 1 and 2, R1s each are independently an alkyl group having 8 to 30 carbon atoms, R2s each are independently hydrogen or a methyl group, As each are independently an alkylene group having 2 to 4 carbon atoms or a substituted alkylene group, ns each are independently an integer from 0 to 200, and Xs each are independently hydrogen or one of substituents represented by the chemical formula 3: 
wherein, in chemical formula 3, Ms each are independently an alkali metal, NH4 or an alkanolamine residue, and R3s each are independently a residue other than X in chemical formula 1 or 2.
An emulsifying agent composition for aqueous resin dispersion according to the present invention comprises: a polymerizable monomer surface active agent represented by the general formula (I) as chemical formula 4: 
and a polymerizable dimer surface active agent represented by the general formula (II) as chemical formula 5: 
wherein, in chemical formulae 4 and 5, R1s each are independently an alkyl group having 8 to 30 carbon atoms, R2s each are independently hydrogen or a methyl group, As each are independently an alkylene group having 2 to 4 carbon atoms or a substituted alkylene group, ns each are independently an integer from 0 to 200, and Xs each are independently hydrogen or one of substituents represented by the chemical formula 6: 
wherein, in chemical formula 6, Ms each are independently an alkali metal, NH4 or an alkanolamine residue, and R3s each are independently a residue other than X in chemical formula 4 or 5.
Since the surface-active agent composition and the emulsifying agent composition for aqueous resin dispersion according to the present invention comprise the polymerizable monomer surface active agent represented by the general formula (I) as chemical formula 1 and the polymerizable dimer surface active agent represented by the general formula (II) as chemical formula 2, they provide for an emulsion exhibiting satisfactory mechanical stability and polymerization stability when they are used in an aqueous-system emulsion polymerization of an ethylenic unsaturated monomer. What is more, they are polymerizable with such an ethylenic unsaturated monomer and hence ensure a film having excellent characteristics. More specifically, use of an emulsion polymer prepared using the surface-active agent composition of the present invention makes it possible to yield a film that is excellent in water resistance, peel strength, adhesion retention and the like.
The foregoing and other objects, features and attendant advantages of the present invention will become apparent from the reading of the following detailed description in conjunction with the accompanying drawings.